Rooster has white tumors at base of feathers.

I have only had chickens a year so I am still new at this. My Rhode Island Red rooster has been hanging his head the last week. I picked him up and noticed on the back of his neck at the base of his feathers he had some sort of growth. They are large white sandstone textured growths. What is it? How can I help my rooster? Is it contagious?

Thank you everyone. Once again you have come through for me. I just had my local chicken expert stop by. His timing was great. He thinks it is mites. He recommended the seven dust plus something called black leaf 40.